Osteocytes Exposed to Titanium Particles Inhibit Osteoblastic Cell Differentiation via Connexin 43.

Periprosthetic osteolysis (PPO) induced by wear particles is the most severe complication of total joint replacement; however, the mechanism behind PPO remains elusive. Previous studies have shown that osteocytes play important roles in wear-particle-induced osteolysis. In this study, we investigated the effects of connexin 43 (Cx43) on the regulation of osteocyte-to-osteoblast differentiation. We established an in vivo murine model of calvarial osteolysis induced by titanium (Ti) particles. The osteolysis characteristic and osteogenesis markers in the osteocyte-selective Cx43 (CKO)-deficient and wild-type (WT) mice were observed. The calvarial osteolysis induced by Ti particles was partially attenuated in CKO mice. The expression of ß-catenin and osteogenesis markers increased significantly in CKO mice. In vitro, the osteocytic cell line MLO-Y4 was treated with Ti particles. The co-culturing of MLO-Y4 cells with MC3T3-E1 osteoblastic cells was used to observe the effects of Ti-treated osteocytes on osteoblast differentiation. When Cx43 of MLO-Y4 cells was silenced or overexpressed, ß-catenin was detected. Additionally, co-immunoprecipitation detection of Cx43 and ß-catenin binding in MLO-Y4 cells and MC3T3-E1 cells was performed. Finally, ß-catenin expression in MC3T3-E1 cells and osteoblast differentiation were evaluated after 18α-glycyrrhetinic acid (18α-GA) was used to block the intercellular communication of Cx43 between MLO-Y4 and MC3T3-E1 cells. Ti particles increased Cx43 expression and decreased ß-catenin expression in MLO-Y4 cells. The silencing of Cx43 increased the ß-catenin expression, and the over-expression of Cx43 decreased the ß-catenin expression. In the co-culture model, Ti treatment of MLO-Y4 cells inhibited the osteoblastic differentiation of MC3T3-E1 cells and Cx43 silencing in MLO-Y4 cells attenuated the inhibitory effects on osteoblastic differentiation. With Cx43 silencing in the MLO-Y4 cells, the MC3T3-E1 cells, co-cultured alongside MLO-Y4, displayed decreased Cx43 expression, increased ß-catenin expression, activation of Runx2, and promotion of osteoblastic differentiation in vitro co-culture. Finally, Cx43 expression was found to be negatively correlated to the activity of the Wnt signaling pathway, mostly through the Cx43 binding of ß-catenin from its translocation to the nucleus. The results of our study suggest that Ti particles increased Cx43 expression in osteocytes and that osteocytes may participate in the regulation of osteoblast function via the Cx43 during PPO.

SOST gene suppression stimulates osteocyte Wnt/ß-catenin signaling to prevent bone resorption and attenuates particle-induced osteolysis.

The most common cause for prosthetic revision surgery is wear particle-induced periprosthetic osteolysis, which leads to aseptic loosening of the prosthesis. Both SOST gene and its synthetic protein, sclerostin, are hallmarks of osteocytes. According to our previous findings, blocking SOST induces bone formation and protects against bone loss and deformation caused by titanium (Ti) particles by activating the Wnt/ß-catenin cascade. Although SOST has been shown to influence osteoblasts, its ability to control wear-particle-induced osteolysis via targeting osteoclasts remains unclear. Mice were subjected to development of a cranial osteolysis model. Micro CT, HE staining, and TRAP staining were performed to evaluate bone loss in the mouse model. Bone marrow-derived monocyte-macrophages (BMMs) made from the C57BL/6 mice were exposed to the medium of MLO-Y4 (co-cultured with Ti particles) to transform them into osteoclasts. Bioinformatics methods were used to predict and validate the interaction among SOST, Wnt/ß-catenin, RANKL/OPG, TNF-α, and IL-6. Local bone density and bone volume improved after SOST inhibition, both the number of lysis pores and the rate of skull erosion decreased. Histological research showed that ß-catenin and OPG expression were markedly increased after SOST inhibition, whereas TRAP and RANKL levels were markedly decreased. In-vitro, Ti particle treatment elevated the expression of sclerostin, suppressed the expression of ß-catenin, and increased the RANKL/OPG ratio in the MLO-Y4 cell line. TNF-α and IL-6 also elevated after treatment with Ti particles. The expression levels of NFATc1, CTSK, and TRAP in osteoclasts were significantly increased, and the number of positive cells for TRAP staining was increased. Additionally, the volume of bone resorption increased at the same time. In contrast, when SOST expression was inhibited in the MLO-Y4 cell line, these effects produced by Ti particles were reversed. All the results strongly show that SOST inhibition triggered the osteocyte Wnt/ß-catenin signaling cascade and prevented wear particle-induced osteoclastogenesis, which might reduce periprosthetic osteolysis. KEY MESSAGES: SOST is a molecular regulator in maintaining bone homeostasis. SOST plays in regulating bone homeostasis through the Wnt/ß-catenin signaling pathway. SOST gene suppression stimulates osteocyte Wnt/ß-catenin signaling to prevent bone resorption and attenuates particle-induced osteolysis.

Krüppel-like factor 4 promotes the proliferation and osteogenic differentiation of BMSCs through SOX2/IGF2 pathway.

OBJECTIVES: Human bone marrow mesenchymal stem cells (BMSCs) have multi-lineage differentiation potential and have been widely researched in regenerative medicine. The purpose of this research was to explore whether Krüppel-like factor 4 (KLF4) can regulate the osteogenic differentiation of BMSCs. METHODS: We transfected human BMSCs with KLF4 overexpression plasmid and si-KLF4 to study the effects of KLF4. We performed cell proliferation assay, flow cytometry and Alizarin Red staining on BMSCs. Quantitative real-time PCR and western blot was performed to determined mRNA and protein expression of osteogenic differentiation markers, KLF4, SOX2 and IGF2. Bone defect animal model was created and the adenovirus containing KLF4 overexpression or knockdown plasmid was injected. Finally, HE staining was performed on tibia to assess the new bone formation. RESULTS: Our results showed that KLF4 promotes not only the growth of BMSCs, but also their osteogenic differentiation. Also, it mediated these effects through SOX2/IGF2 signaling pathway. In addition, KLF4 overexpression could increase the bone regeneration in in-vivo model, whereas KLF4 knockdown decreased the bone regeneration. CONCLUSIONS: KLF4 regulates BMSC's osteogenic differentiation via SOX2/IGF2 pathway.

Posterior Locking Plate Fixation of Bartonícek Type IV Posterior Malleolar Fracture: A Focus on Die-Punch Fragment Size.

Die-punch fragments refer to articular cartilage and subchondral bone embedded in cancellous bone as part of an intra-articular fracture. Bartonícek type IV posterior malleolar fractures with associated die-punch fragments are rare, and the appropriate surgical approach remains unclear. We determined outcomes, and the effect of die-punch fragment size on outcomes, for 32 patients with Bartonícek type IV posterior malleolar fractures with die-punch fragments between January 2015 and December 2017. Mean follow-up for all patients was 23.8 (range 20.0-30.0) months. At the final follow-up visit, mean ankle dorsal extension was 24.6° and plantar flexion was 40.0°; American Orthopaedic Foot and Ankle Society ankle-hindfoot score was 88.6 ± 4.3; visual analog scale weightbearing pain score was 1.5 ± 0.6; and Bargon traumatic arthritis score was 0.8 ± 0.4. There were no severe complications. We divided patients into a small-fragment (≤3 mm) group (n = 12) and large-fragment (>3 mm) group (n = 20). The Bargon scores at final follow-up were 0.5 and 1, respectively (P=.02). There were no statistically significant differences between the 2 groups for the other outcome scores at various time intervals. The posterolateral approach with distal locking plate internal fixation for Bartonícek type IV posterior malleolar fractures with die-punch fragments can result in excellent anatomical reduction of the collapsed articular surface and the displaced fragment from the tibial plafond, recovery of articular surface congruity, and maintenance of joint stability. Die-punch fragment size may not impact clinical and functional outcomes but may contribute to post-traumatic arthritis.

The CT morphological characteristics and the clinical management strategy of posterior malleolar fractures with talar subluxation.

BACKGROUND: The optimal clinical treatment and the computed tomography (CT) morphological characteristics of posterior malleolar fractures (PMF) with talar subluxation remain inconclusive. Clinically, both plate screws and lag screws are widely used to fix posterior malleolar fragments using a direct or indirect approach. We sought to summarize the morphological characteristics and modified classification on the basis of CT and the intraoperative strategy for posterior talar subluxation in PMF. METHODS: Retrospectively, 46 adult PMF patients with subluxations of the talus were recruited as the study cohort. According to its morphological features, PMF with subluxation of the talus can be divided mainly into two types using this modified classification: a complete fracture (the single-fragment type) and PMF with two-angled fracture fragments (the double-fragment type). The cohort's demographic information, classifications, fracture morphology, fixation methods, pain levels, and functional scores were recorded for both fracture types. RESULTS: The average values of the depths and heights of the posterior malleolar fragments were (29.1±7.3) mm for the single-fragment type and (17.9±4.2) mm for the double-fragment type. There was a significant difference in the mean values between the two types (P < 0.05). Posterior plate fixation was suitable for the single-fragment type, while antero-posterior and postero-anterior (AP-PA) lag screws fixations were made available for the double-fragment type. Both methods achieved good results. No significant differences were found in terms of sex, age, body mass index (BMI), side, Haraguchi classification, Bartonícek and Rammelt classification, Visual Analog Scale (VAS) scores, or American Orthopedic Foot & Ankle Society scores (AOFAS) when comparing the single-/double-fragment type groups after the mid-term follow-up (P > 0.05). CONCLUSION: According to the injury mechanism and the morphological characteristics of the fractures, the proposed improved classification system for PMF with subluxation of the talus based on the injury mechanism and the fracture morphology can provide guidance for surgical management strategies and achieve optimal outcomes.

Treatment of nonunion after femoral neck fracture with valgus intertrochanteric osteotomy: a case report with 18-year follow-up.

We herein report the long-term effect of valgus intertrochanteric osteotomy for nonunion after femoral neck fracture. In this report, we describe our experience using valgus intertrochanteric osteotomy to treat nonunion after femoral neck fracture in a 20-year-old woman. The patient was discharged from the hospital 10 days after the operation, the internal fixation device was removed 1 year after the operation, and the patient was then followed up for 18 years. Valgus intertrochanteric osteotomy can effectively treat nonunion after adductive femoral neck fracture.

Efficacy and safety of local infiltration analgesia for pain management in total knee and hip arthroplasty: A meta-analysis of randomized controlled trial.

BACKGROUND: Local infiltration analgesia (LIA) has become popular in postoperative pain relief after total hip arthroplasty (THA) or total knee arthroplasty (TKA). The aim of this meta-analysis was to compare the efficacy and safety of LIA with intrathecal morphine and epidural analgesia after THA and TKA. METHODS: A systematic article search was performed from PubMed, Embase, and Web of Science databases, up to February 21, 2019. The main outcomes included visual analog scale for assessment of pain, morphine equivalent consumption, length of hospital stay, and adverse events. The data were calculated using weight mean difference (WMD) or risk ratio (RR) with 95% confidence intervals (95% CIs). RESULTS: Eleven studies with a total of 707 patients met the inclusion criteria and were included in this meta-analysis. LIA provided better pain control than other 2 techniques at 24-hour (WMD = 10.61, 95% CI: 3.36-17.87; P = .004), 48-hour (WMD = 16.0, 95% CI: 8.87-23.13; P < .001), and 72-hour (WMD = 11.31, 95% CI: 3.78-18.83; P < .001). Moreover, LIA had similar morphine consumption and duration of hospital stay with intrathecal morphine and epidural analgesia. There was significantly lower incidence of adverse events with LIA than with the other 2 techniques. CONCLUSION: LIA provided better postoperative pain control and less adverse events than intrathecal morphine and epidural analgesia after THA and TKA.

Risk Factors for Surgical Site Infection After Spinal Surgery: A Systematic Review and Meta-Analysis Based on Twenty-Seven Studies.

BACKGROUND: The present meta-analysis was conducted to explore and identify the risk factors for surgical site infection (SSI) after spinal surgery based on qualified studies and to gain insight into the management of SSI among patients undergoing spinal surgery. METHODS: We searched the following electronic databases, PubMed, the Cochrane Library, and the Embase database, updated to May 2018, to identify eligible studies according to the index words with associated publications. The odds ratios and 95% confidence intervals were used to analyze the main outcomes. RESULTS: We found 27 studies with a total of 2175 patients in the SSI group and 41,536 patients in the control group for the present meta-analysis. The pooled results revealed that the risk factors for SSI included diabetes, obesity, hypertension, ≥3 hours operative time, and transfusion. In addition, no significant association was found between SSI and the following risk factors: female gender, age >60 years, smoking habit, bone autograft, bone allograft, prophylactic antibiotics, and steroid therapy. CONCLUSIONS: Our findings provide evidence that diabetes, obesity (body mass index >30 kg/m2), hypertension, ≥3 hours operative time, and transfusion have a strong association with a remarkable increase in the risk of SSI after spinal surgery. In conclusion, more high-quality trials with larger sample sizes and long-term randomized controlled trials are warranted to confirm the risk factors for SSI among patients undergoing spinal surgery.

Static Compression Induces ECM Remodeling and Integrin α2ß1 Expression and Signaling in a Rat Tail Caudal Intervertebral Disc Degeneration Model.

STUDY DESIGN: A three-level rat tail caudal intervertebral disc (IVD) degeneration (IVDD) model was established to study effects of static compression on extracellular matrix (ECM) remodeling and integrin signaling in IVDs during IVDD. OBJECTIVE: The aim of this study was to investigate the effect of compression force on ECM remodeling and integrin signaling in IVDs during IVDD. SUMMARY OF BACKGROUND DATA: Integrins sense mechanical environment alteration via binding to ECM ligands and trigger intracellular signaling for pathological ECM remodeling during IVDD. However, the role of compression force in ECM remodeling and integrin signaling during IVDD remains elusive. METHODS: Compared with the classical one-level rat tail IVDD model that exerts axial stress on the 8th to 9th caudal vertebral bodies, a three-level model was established by using an Ilizarov-type apparatus to exert stress on the 7th to 10th caudal vertebral bodies in rat tails for four weeks. To exclude side effects from surgical stab injury on manipulated discs, intact coccygeal (Co) disc Co8-9 was analyzed. RESULTS: In three-level IVDD model, significant degeneration of the Co8-9 disc was observed. Quantitative real-time polymerase chain reaction (qRT-PCR) showed elevated mRNA expression of collagen types I, III, and V; matrix metalloproteinases (MMPs) 2, 3, 9, 13, 14; and decreased mRNA expression of collagen type II in Co8-9 disc. Compression loading altered the expression of integrin α2ß1 (upregulated) and α10ß1 (downregulated) in NP cells, and activated integrin downstream signaling. By contrast, one-level model showed more severe disc degeneration and ECM remodeling. Integrin α1, α2, α11, and ß1 were upregulated, whereas α10 was downregulated. Similar activation of integrin signaling was observed. CONCLUSION: Static compression altered collagen and MMP expression, and promoted ß1 integrin expression and signaling in IVD. Compared with one-level rat tail IVDD model, three-level model showed milder effects on disc degeneration, ECM remodeling, and integrin expression, suggesting one-level model might involve other causes that induce IVDD via mechanisms independent of compression force. LEVEL OF EVIDENCE: N/A.

Ertapenem versus ceftriaxone for the treatment of complicated infections: a meta-analysis of randomized controlled trials.

BACKGROUND: Ertapenem has been demonstrated to be highly effective for the treatment of complicated infections. The aim of this study was to compare the efficacy and safety of ertapenem with ceftriaxone. METHODS: We searched the PubMed, EMBASE, and the Cochrane Library for published randomized controlled trials (RCTs) that compared the efficacy and safety of ertapenem with ceftriaxone for the treatment of complicated infections including community-acquired pneumonia (CAP), complicated urinary tract infections (cUTIs), and complicated intra-abdominal infections (cIAIs). Meta-analysis was performed by RevMan 5.0. RESULTS: Eight RCTs, involving 2 883 patients, were included in our meta-analysis. Ertapenem was associated with similar clinical treatment success with ceftriaxone for complicated infections (1 326 patients, fixed-effect model, OR: 1.13, 95% CI: 0.75-1.71). There was no difference between the compared treatment groups with regard to the microbiological treatment success, and no difference was found with regard to the incidence of clinical and laboratory drug-related adverse events between ertapenem and ceftriaxone groups. As to local tolerability, overall, there was no difference between the compared groups; however, in the subgroup analysis, local reaction was significantly less in the ertapenem subgroup than the ceftriaxone plus ceftriaxone subgroup. CONCLUSIONS: Ertapenem can be used as effectively and safely as ceftriaxone for the treatment of complicated infections. It is an appealing option for the treatment of these complicated infections.

Determination of thalidomide concentration in human plasma by liquid chromatography-tandem mass spectrometry.

A rapid, sensitive and specific analytical method based on high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the determination of thalidomide concentration in human plasma. The analyte and internal standard were extracted by liquid-liquid extraction with ether-dichloromethane (3:2, v/v) and separated on a TC-C(18) column using methanol-10 mM ammonium acetate-formic acid (60:40:0.04, v/v/v) as the mobile phase at a flow rate of 0.9 ml/min. The detection was performed using an API 4000 triple quadrupole mass spectrometer in the positive electrospray ionization (ESI) mode and completed within 3.0 min. The multiple reaction monitoring (MRM) transitions were m/z 259.1→84.0 for the analyte and m/z 195.9→138.9 for temozolomide. The calibration curve exhibited a linear dynamic range of 2-1500 ng/ml (r>0.9991). The intra-and inter-day precisions (as relative standard deviation; RSD) were 6.8-13.5% and 4.3-5.0% respectively and the accuracy (as relative error; RE) was 2.0-3.5%. The recoveries and matrix effects were satisfactory in all the biological matrices examined. This method was successfully used in a pharmacokinetic study of thalidomide in healthy male volunteers receiving an oral administration of a 200-mg dose.

Treatment of community-acquired pneumonia with moxifloxacin: a meta-analysis of randomized controlled trials.

Community-acquired pneumonia (CAP) is a leading cause of morbidity and mortality throughout the world. To investigate whether moxifloxacin monotherapy is associated with better clinical outcomes than other antibiotics recommended for CAP among adults with mild-to-moderate or severe CAP, we performed a meta-analysis. MEDLINE, EMBASE, Web of Science, and the Cochrane Library were searched for randomized control trials (RCTs). The efficacy and safety of moxifloxacin were compared with other antimicrobial agents used to treat CAP. Fourteen RCTs, consisting of 6923 total patients, were included in the meta-analysis. No difference was found regarding the incidence of adverse events and mortality between moxifloxacin and the compared regimens. We found that moxifloxacin is as effective and well-tolerated as other recommended antibiotics for the treatment of CAP and possesses a better pathogen eradication rate than beta-lactam-based therapy.

Susceptibility of Gram-negative bacteria to isepamicin: a systematic review.

We sought to review the potential role of isepamicin against infections with contemporary Gram-negative bacteria. We searched PubMed and Scopus databases to identify relevant microbiological and clinical studies published between 2000 and 2010, and we retrieved 11 and three studies, respectively. A total of 4901 isolates were examined in the in vitro studies. Isepamicin had higher in vitro activity compared with amikacin in four studies, was as active as amikacin in six studies and in the remaining study both were inactive. Regarding specifically the studies that included multidrug-resistant bacteria, isepamicin appeared superior to amikacin in two studies, as active as amikacin in one study and both did not exhibit activity in one study. In the clinical studies, isepamicin was as active as amikacin for the treatment of 55 children with urinary tract infections. In conclusion, isepamicin might be active in vitro against Gram-negative bacteria with resistance to amikacin and other aminoglycosides.

In vitro activity of minocycline combined with fosfomycin against clinical isolates of methicillin-resistant Staphylococcus aureus.

This study aimed to evaluate the in vitro activity of minocycline combined with fosfomycin against isolates of methicillin-resistant Staphylococcus aureus (MRSA). A total of 87 clinical isolates of MRSA collected from three Chinese hospitals were included in the study. The checkerboard method with determination of the fractional IC index (FICI) was used to determine whether antibiotic combinations act synergistically against these isolates. The susceptibility results for minocycline and fosfomycin were interpreted according to the most relevant criteria. The results demonstrated the following interactions: 76 isolates (87.4%) showed synergistic interactions (FICI0.5) and 11 isolates (12.6%) showed indifferent interactions (0.5

Heterologous expression characteristics of Trichoderma viride endoglucanase V in the silkworm, Bombyx mori L.

Efficient degradation of cellulose needs a synergistic reaction of the cellulolytic enzymes, which include exoglucanases, endoglucanases, and ß-1,4-glucosidase. In this study, we used an improved Bac-to-Bac/BmNPV baculovirus expression system, which lacks the virus-encoded chitinase cathepsin (v-cath) genes of Bombyx mori nucleopolyhedrovirus (BmNPV), to express the endoglucanase V (EG V) gene from Trichoderma viride in silkworm BmN cells and silkworm larvae, and analyzed the characteristics of the recombinant enzyme in silkworm larvae. The result showed that an around 36-kDa protein was visualized in BmN cells at 48 h after the second-generation recombinant mBacmid/BmNPV/EG V baculovirus infection. The crude enzyme extract from the recombinant baculoviruses-infected silkworms exhibited a significant maximum activity at the environmental condition of pH 5.0 and a temperature of 50 °C, and increased 39.86% and 37.76% compared with that from blank mBacmid/BmNPV baculovirus-infected silkworms and normal silkworms, respectively. It was stable at pH range from 5.0 to 10.0 and at temperature range from 40 to 60 °C. The availability of large quantities of EG V that the silkworm provides might greatly facilitate the future research and the potential application in industries.

Cloning and characterization of the Bombyx mori ecdysone oxidase.

The physiological titer of molting hormones in insects depends on relative activities of synthesis and degradation pathways. Ecdysone oxidase (EO) is a key enzyme in the inactivation of ecdysteroid. However, there are only a few reports on ecdysteroid inactivation and its enzymes in silkworm. In this study, we cloned and characterized the Bombyx mori EO (BmEO). The BmEO cDNA contains an ORF of 1,695 bp and the deduced protein sequence contains 564 amino acid residues. The deduced protein sequence contains two functional domains of glucose-methanol-choline oxidoreductase in N-terminal and C-terminal. Comparing the expression levels of BmEO in different tissues, high transcription was mainly present in hemocytes. Reduced expression of this enzyme is expected to lead to pathological accumulation of ecdysone in the hemolymph of silkworm larvae or pupae. Our data show that RNA inference of BmEO transcripts resulted in the accumulation of ecdysteroid and death of larvae or pupae. We infer that EO is a crucial element in the physiology of insect development.

Cloning and expression pattern of 3-dehydroecdysone 3ß-reductase (3DE 3ß-reductase) from the silkworm, Bombyx mori L.

Molting in insects is regulated by molting hormones (ecdysteroids), which are also crucial to insect growth, development, reproduction, etc. Ecdysone was inactivated to 3-dehydroecdysone (3DE) under ecdysone oxidase (EO), and followed by NAD(P)H-dependent irreversible reduction to 3-epiecdysteroid under 3DE 3a-reductase. On the other hand, 3-dehydroecdysone undergoes reversible reduction to ecdysone by 3DE 3ß-reductase in the hemolymph. In this article, we cloned and characterized 3-dehydroecdysone 3ß-reductase (3DE 3ß-reductase) in the different tissues and the developing stage from the silkworm, Bombyx mori L. The B. mori 3DE 3ß-reductase cDNA contains an ORF 972 bp and the deduced protein sequence containing 323 amino acid residues. Analysis showed that the deduced 3DE 3ß-reductase belongs to the aldo-keto reductase (AKR) superfamily, which has the NAD(P)-binding domain, indicating that the function of 3DE 3ß-reductase depends on the existence of NAD(P)H. Using Escherichia coli, a high level expression of a fusion polypeptide band of approx. 40 kDa was observed. The high transcription of 3DE 3ß-reductase was mainly observed in the genitalia and fatty bodies in the third day of the fifth-instar larvae, followed next in the head, epidermis, and hemocytes. The expression of 3DE 3ß-reductase in the early of every instar was lower than that in the late of instar. When the titer of 3DE is low, higher expression of 3DE 3ß-reductase is necessary to maintain the ecdysone titer in body through converting 3DE to ecdysone, while the 3DE titer is high, the expression of 3DE 3ß-reductase showed feedback inhibition.

Expression of Trichoderma viride endoglucanase III in the larvae of silkworm, Bombyx mori L. and characteristic analysis of the recombinant protein.

Endoglucanase is a part of cellulase which hydrolyzes cellulose into glucose. In this study, we cloned endoglucanase III (EG III) gene from Trichoderma viride strain AS 3.3711 using a PCR-based exon splicing method, and expressed EG III recombinant protein in both silkworm BmN cell line and silkworm larvae with an improved Bac-to-Bac/BmNPV mutant baculovirus expression system, which lacks the chiA and v-cath genes of Bombyx mori nucleopolyhedrovirus (BmNPV). The result showed that around 45 kDa protein was visualized in BmN cells at 48 h after the second generation recombinant mBacmid/BmNPV/EG III baculovirus infection. The enzymes from recombinant baculoviruses infected silkworms exhibited significant maximum enzyme activity at the environmental condition of pH 8.0 and temperature 50°C, and increased 20.94 and 19.13% compared with that from blank mBacmid/BmNPV baculoviruses infected silkworms and normal silkworms, respectively. It was stable at pH range from 5.0 to 9.0 and at temperature range from 40 to 60°C. It provided a possibility to generate transgenic silkworms expressing bio-active cellulase, which can catabolize dietary fibers more efficiently, and it might be of great significance for sericulture industry.

Identification and characterization of two chitin-binding proteins from the peritrophic membrane of the silkworm, Bombyx mori L.

The peritrophic membrane (PM) is a semi-permeable lining of the insect midgut, broadly analogous to the mucous lining of vertebrate gut. The PM proteins are important achievements for the function of the PM. In this study, two chitin-binding proteins (BmPM-P43 and BmPM-P41) from the PM of the silkworm, Bombyx mori, were identified and cloned. These proteins showed the molecular mass of 43 and 41 kDa, respectively. The deduced amino acid sequences codes for a protein of 381 amino acid residues and 364 amino acid residues, containing 12 and 14 cysteine residues followed by similar domain, both of them have 5 cysteine residues in similar position in the C-terminal. The confirmation of these proteins was performed by western blot analysis of recombinant BmPM-P43 and BmPM-P41. The chitin-binding activity analysis showed that the BmPM-P43 and BmPM-P41 could bind to chitin strongly. It is concluded that BmPM-P43 and BmPM-P41 contains a polysaccharide deacetylase domain instead of peritrophin domain, indicated that these two proteins may belong to a new chitin-binding protein family.

Cloning and expression of a cellulase gene in the silkworm, Bombyx mori by improved Bac-to-Bac/BmNPV baculovirus expression system.

Cellulases catalyze the hydrolysis of cellulose which are mainly three types: endoglucanases, cellobiohydrolases and ß-glucosidases. It can be used in converting cellulosic biomass to glucose that can be used in different applications such as production of fuel ethanol, animal feed, waste water treatment and in brewing industry. In this paper, we cloned a 1380-bp endoglucanase I (EG I) gene from mycelium of filamentous fungus Trichoderma viride strain AS 3.3711 using PCR-based exon splicing methods, and expressed the recombinant EG I mature peptide protein in both silkworm BmN cell line and silkworm larvae with a newly established Bac-to-Bac/BmNPV mutant baculovirus expression system, which lacks the virus-encoded chitinase (chiA) and cathepsin (v-cath) genes of Bombyx mori nucleopolyhedrovirus (BmNPV). An around 49-kDa protein was visualized after mBacmid/BmNPV/EG I infection, and the maximum expression in silkworm larvae was at 84 h post-infection. The ANOVA showed that the enzymes from recombinant baculoviruses infected silkworms exhibited significant maximum enzyme activity at the environmental condition of pH 7.0 and temperature 50°C. It was stable at pH range from 5.0 to 10.0 and at temperature range from 50 to 60°C, and increased 24.71 and 22.84% compared with that from wild baculoviruses infected silkworms and normal silkworms, respectively. The availability of large quantities of EG I that the silkworm provides maybe greatly facilitate the future research and the potential application in industries.